Effect of Inorganic Ions on Binding Affinity and Capacity of Arginine Vasotocin Receptors of the Hen Uterus (Shell Gland) in Radioligand Assays

Abstract

Binding affinity of arginine vasotocin (AVT) receptor of the hen uterus, estimated from the equilibrium dissociation constant (Kd) by SCATCHARD analysis (1949), was found to decrease by the presence of Ca²⁺ or Mg²⁺ at a concentration of 1 or 2mM in buffer solution and to increase by the presence of PO₄^3- or a chelating agent, EDTA. Binding capacity (maximum number of binding sites: NBSmax) was decreased by the presence of PO₄^3- or Ca²⁺ at the concentration of 2mM, but not by the presence of Mg²⁺ at the same concentration.